The discovery of a potent class of herbicidal compounds, known as the imidazolinone compounds, has resulted in considerable field testing of these compounds both alone and in combination with other herbicides for various uses worldwide.
Herbicidal substituted pyridine and quinoline-2-imidazolin-2-yl acids, esters and salts are disclosed in European Pat. No. 0 041 623, which also describes aqueous compositions of water soluble salts of herbicidal pyridine and quinoline-2-imidazolin-2-yl acids which may simply be dispersed in water and applied as a dilute aqueous spray to the foilage of plants or to soil containing propagating organs thereof. Herbicides such as the 2,6-dinitroanilines, are, due to their low water solubility, normally applied as aqueous emulsions that are prepared from organic based emulsifiable concentrate compositions.
Since the use of herbicidal combinations for the control of undesirable vegetation is a well established practice, it is desirable to have stable combination compositions containing water soluble herbicidal imidazolinone acids such as 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-3-quinolinecarboxylic acid salts and herbicidal 2,6-dinitroaniline compounds which have a low degree of water solubility such as N-(1-ethylpropyl)-2,6-dinitro3,4-xylidine, (pendimethalin), and alpha,alpha,alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine (trifluralin).
A single composition containing both of these classes of herbicides would avoid the problems of handling, measuring and mixing which is associated with the practice of preparing tank-mixtures of individual formulations prior to spraying. Pending application for U.S. Letters Patent of J. Parsons, Ser. No. 880,446, filed June 30, 1986 describes nonaqueous liquid concentrate compositions of salts of 2-(4-isopropyl-4-methyl-5- oxo-2-imidazolin-2-yl)-3-quinolinecarboxylic acid which are suitable for the preparation of nonaqueous combination compositions containing herbicidal dinitroaniline compounds. However, an aqueous combination composition for these classes of herbicides has not been described. Herbicidal compositions which have been described as concentrated aqueous emulsions or concentrated oil in water emulsions containing a single water insoluble herbicide in a water insoluble solvent which is emulsified in an aqueous phase and their advantages have been described in various publications.
UK Patent Application No. GB 2,115,285A describes a concentrated aqueous emulsion containing on specific weight bases one or more liquid herbicidal phenoxyalkanecarboxylic acid esters, one or more oil soluble emulsifiers, and a water soluble dispersant as aqueous emulsions. U.S. Pat. No. 4,460,406 describes concentrated oil in water emulsion formulations containing an organic solvent soluble 2-haloacetanilde or thiocarbamate herbicide having a solution point below 25.degree. C., a hydrocarbon solvent, a non-ionic emulsifying agent having an HLB of 18 or greater, a C.sub.14 -C.sub.20 straight chain alcohol, and water containing an agriculturally acceptable salt or urea, all according to specific concentration ranges. U.S. Pat. No. 4,174,960 describes concentrated aqueous emulsions containing one or more water insoluble herbicidal 2,6-dinitroaniline derivatives, a water immiscible solvent, an emulsifying agent and an aqueous solution containing an inorganic salt. Additionally, in the case of 2-haloacetanildes the use of this type of formulation has been extended to the development of concentrated emulsion compositions of these water-insoluble herbicides with water soluble N-phosphonomethylglycine salts as disclosed in U.S. Pat. No. 4,440,562 which describes compositions containing, according to highly specific weight ranges, the isopropylamine salt of N-phosphonomethylglycine; a surfactant therefor; 2-chloro-2',6'-diethyl-N-(methoxymethyl)acetanilide; an organophilic clay; an emulsifier selected from the group consisting of alkylaryl sulfonates, phosphate esters of nonylphenol ethoxylates and polyalkyleneglycol ethers; an organic solvent in which 2-chloro-2'6'-diethyl-N-(methoxymethyl)acetanilide herbicide is soluble, which is nonreactive to said herbicide and which is essentially water-insoluble; and the balance being made up of water.
It is an object of this invention to provide novel concentrated oil in water emulsion combination compositions of water soluble salts of herbicidal imidazolinyl acids and 2,6-dinitroaniline herbicides, and a method for their preparation.